Examining the Overlap Between ADHD and Autism Spectrum Disorder (ASD) Using Candidate Endophenotypes of ADHD

Objective: Recent discussions of aetiological overlap between ADHD and Autism Spectrum Disorder (ASD) require comparative studying of these disorders.

METHOD

We examined performance of ASD patients with (ASD+) and without (ASD-) comorbid ADHD, ADHD patients, and controls for selected putative endophenotypes of ADHD: Intrasubject Variability (ISV) of reaction times, working memory (WM), inhibition, and temporal processing.

RESULTS

We found that patients with ADHD or ASD+, but not ASD-, had elevated ISV across the entire task battery and temporal processing deficits, and that none of the groups were impaired in WM or inhibition. High levels of ISV and generally poor performance in ASD+ patients were only partially due to additive effects of the pure disorders.

CONCLUSION

Overall, we conclude that, within our limited but heterogeneous task battery, ISV and temporal processing deficits are most sensitive to ADHD symptomatology and that controlling for ADHD comorbidity is mandatory when assessing ISV in autism.

Cognitive processes during deception about attitudes revisited: a replication study

Event-related potential (ERP) studies about deception often apply recognition tasks. It remains questionable whether reported ERP patterns and cognitive processes can be generalized to other contexts. As the study by Johnson et al. (2008) fills this gap by investigating deception regarding attitudes, we tried to replicate it. Participants (N = 99) were instructed to lie or tell the truth about their attitudes. We obtained the same results as Johnson et al. (2008): lies were accompanied by enhanced medial frontal negativities (MFN) and suppressed late positive components (LPCs) indicating that lying relied on stronger cognitive control processes and response conflicts than being honest. The amplitudes of pre-response positivities (PRP) were reduced for lies implying that lies about attitudes were accompanied by strategic monitoring. MFN amplitudes increased and LPC amplitudes decreased for lies about positively valued items revealing that lying about positively valued items is cognitively more challenging than lying about negatively valued items. As a new finding, MFN, LPC and PRP components were neither moderated by Machiavellianism nor by changes in the attitude ratings. The results indicate that LPC, MFN and PRP components are reliable indicators of the cognitive processes used during deception and that it is worthwhile to investigate them in further deception contexts.

Trauma severity and initial reactions as precipitating factors for posttraumatic stress symptoms and chronic dissociation in former political prisoners

This study explores the relationships among trauma severity, initial trauma reactions, posttraumatic stress disorder (PTSD) symptoms, and dissociation in a group of 98 former East-German political prisoners. Trauma severity and initial reactions were assessed using a persecution checklist and a coping process questionnaire. PTSD symptoms were assessed through a structured clinical interview. Chronic dissociation was evaluated using the Dissociative Experiences Scale. The two assumptions of the study were confirmed by structural equation modeling: (1) Lifetime PTSD symptoms were predominantly predicted by initial reactions to trauma and (2) chronic dissociation was predominantly predicted by trauma severity. The first finding is discussed in relation to the participants' initial trauma processing. The second finding is discussed especially in the context of trauma duration and dissociation-prone coping attempts. Limitations concerning the long-term interval between traumatization and data collection are discussed.

Is resting anterior EEG alpha asymmetry a trait marker for depression? Findings for healthy adults and clinically depressed patients

Several lines of evidence suggest that asymmetric anterior brain activation is related to affective style, linking left hemisphere activation to positive affect and right hemisphere activation to negative affect. However, previous reports of left frontal hypoactivation in depressed patients were not confirmed in recent studies. This study evaluated additional characteristics of resting EEG alpha (8-13 Hz) asymmetry in 15 clinically depressed patients and 22 healthy adults by recording EEG activity on two separate occasions, 2-4 weeks apart. Across both sessions, group differences in anterior EEG asymmetry were compatible with the original hypothesis. However, groups differed in temporal stability of anterior EEG asymmetry, which was retest reliable in controls but not depressed patients. In contrast, temporal stability of posterior EEG asymmetry was acceptable in both groups. Increased variability of anterior EEG asymmetry may be a characteristic feature for depression, and, if so, this would challenge the notion that anterior EEG alpha asymmetry is a trait marker for depression.

Sensation seeking and affective disorders: characteristics in the intensity dependence of acoustic evoked potentials

Augmenting/reducing of the evoked potential has been shown to be related to sensation seeking (SS) and specific clinical disorders. Buchsbaum demonstrated that patients with bipolar affective disorders (BAD) tend to be augmenters, as is the case with sensation seekers, and patients with unipolar affective disorders (UPD) tend to be reducers. In addition, he reported that prophylactic medication reduced the tendency to augment in bipolar patients. However, evidence for these relations is restricted to a few studies. This study explores whether Buchsbaum's initial findings can be found in a naturalistic clinical setting. Acoustic evoked potentials were recorded for six levels of intensity (59, 71, 79, 88, 92, 96 dB SPL) from 24 healthy adults, 21 unipolar depressed patients, and 21 patients with BAD. Participants also completed personality questionnaires, especially the Sensation Seeking Scales Form V. Results revealed a positive correlation between SS and augmenting/reducing in healthy controls, thereby replicating earlier findings. Bipolar depressed patients showed larger P1/N1 slopes than healthy controls, when medication was statistically controlled. Unipolar depressed patients showed smaller P2 slopes, but only when medication was not controlled. Implications of these results for further research on augmenting/reducing and affective disorders and their relationship to SS are discussed.

[Posner's theory of attention: right hemisphere processing advantage in extended attention]

Posner proposed a theory of attention based on target detection, visual orienting, and alertness. The latter is supposed to use brain structures mainly located in the right hemisphere. Whitehead found a right hemisphere processing superiority during sustained attention. An additional auditory stimulus is thought to produce a change of alertness and should interfere with this asymmetry, which Whitehead was able to show, too. It remains unclear how the left hemisphere is activated by right hemisphere pathways. Therefore we tried to replicate Whitehead's findings. In our first experiment the expected interaction between visual field, foreperiod duration, and tone was obtained. Probably the tone used in our experiment was not intense enough to produce a sufficient change in alertness. We used a more intense tone in a second experiment. This time a three-way interaction was present but could not be interpreted in terms of Whitehead's assumptions. Instead, the additional alerting stimulus seems to influence the state of alertness in a much more general and long-lasting way.